Of the nootropic drugs, I've tried:
piracetam
oxiracetam
aniracetam
pramiracetam
nefiracetam
picamilon
hydergine
vinpocetine
DMAE
Piracetam is a good nootropic, maybe still one of the best, but some people require increased choline when taking it to stave off depression. I used to eat that stuff like candy, but then after a few years I started getting irritable from it so I stopped. Then when I tried it again a few years later, I got some upper right quadrant pain, I thought it might have something to do with liver choline metab, but maybe it was something else.
Oxiracetam seems to increase focus the best, almost to the point where your emotions are kind of "submerged." Can make you very "matter of fact," in my experience, and also increase OCD a little.
Aniracetam completely fogged my brain, almost to the point of feeling completely "blank," and vinpocetine now does that also, although at one point it worked well for me. Ani has effects on AMPA receptors, and I think vinpo is a potassium channel blocker. Those were the mechanism I attributed the fog to, although who really knows, b/c I think piracetam has some AMPA effects, too, and it doesn't do that to me. If ani works for you, I think it's one of the more potent ones.
Pramiracetam made me really irritable so I didn't try it again, and nefiracetam has some potentially bad side effects for males, although the studies were on dogs and it's not clear if those effects extend to humans. I didn't think the risk was worth the meager benefits, though, so I didn't continue that one, either. Seemed like it was no better than just plain old piracetam.
DMAE really screwed up my cognition from just a single dose, but I thought that might have more to do with idiosyncratic methylation issues than the drug itself. Hydergine was pretty good, as I recall, but some people can be allergic to it and have anaphylaxis & other reactions. Have to be careful.
For brain blood flow, picamilon is very likely the best, although I think vinpocetine has some good cerebral blood flow enhancing effects, too. For picamilon, I think it's because pic is niacin bound GABA, and the niacin probably causes some vasodilatation. Right now picamilon is my favorite nootropic. I guess because of the GABA and the fact that it actually crosses the BBB, as opposed to plain GABA, it has some anxiolytic properties. If you take too much, you can definitely feel a slight headachey feeling a few hours later from the vaso effects. It's also said to have some restorative effects following trauma, burnout, etc., maybe above and beyond some of the others. For some people I've heard it doesn't do anything, and I guess that's pretty much the case with all of these: the effectiveness of any particular smart drug probably vary widely from person to person. Trial and error. ;- )